1. Field of Invention
This invention relates to valve seat structures which are operable to block fluid flow along both opposing directions and a flow line. More specifically, the present invention relates to a bi-directional valve seat which experiences enhanced seal in response to flow pressure occurring within the valve.
2. Prior Art
Many valve seat designs have been developed to enable bi-directional flow within a valve operated flow line. The significance of pressure-assisted valve control is that as flow line pressure increases, the sealing contact between the seating member and blocking member which is usually rotated across the flow line also increases. The result is an improved sealing contact which increases with the increasing pressure of the blocked fluid. Accordingly, the stronger the pressure and effort of the fluid to by-pass the valve, the greater is the resistance to valve failure or loss of sealing contact.
One problem which is typically inherent in each valve design is the slight displacement of the blocking member within the flow line as it encounters the immediate pressure buildup of blocked fluid. This displacement of the blocking member naturally follows the flow line of fluid. Even with delicate engineering to minimum tolerances, there is typically some displacement of the blocking member with the initial surge of fluid thereagainst.
In view of the difficulty of designing a bi-directional valve which responds along both directions of displacement of the blocking member, many valve designs have arisen. These are generally characterized by complex geometries for the seating member or sealing member (referred to hereafter as "seating member"), as well as complex construction. Such complexity in high pressure valve systems not only increases expense, but generates higher risk of failure because of failure of the actual valve to meet the complex specification in every instance of manufacture. In other words, commercial development of such valve designs may easily fall below the engineered design criteria because of difficulty of manufacture.